Radak: Why did you come to My land? You are my neighbors - you should have benefited My nation! You did not - rather, when you saw that kings of nations gathered against them to plunder them, you joined with them to plunder.

Radak citing Targum Yonasan: What is your importance in front of Me?

Malbim: The nations to whom I handed over Yisrael, e.g. Ashur and Bavel, they went overboard. The root of what they did evil was Hashem's decree. What are you to Me, Tzor, Tzidon and Gelilos Pelashes? I did not hand over Yisrael to you at all. Who commanded you to do evil to them?!

Radak: This is like Gevulim (borders).

Rashi: This refers to what Shlomo gave to Chiram Melech Tzor - 20 cities (Melachim I, 9:11).

Radak: Gemul is the first benefit that one does to his friend, or the first evil. This is like "Ki Gamal Alai" (Tehilim 13:6). Gemul can refer to returning good or evil, e.g. when it is written regarding payment. Here, the Hei introduces a question. Why do you do evil to Me? If you want to take vengeance against Me, for I did evil to you - what evil did I do to you?

Malbim: What Gemul do you pay to Me? What evil did I do to you? Meshalem Gemul is repaying evil that he received amidst hatred.

Radak: If you will say that you yourselves bestow evil to Me, for one who does evil to Yisrael, his intent is to do evil to Me, for they are My children - if so, I will speedily return your Gemul on your heads!

Malbim: Gomel Gemul is even if he did not receive evil from him. If you do so, even though I did not harm you, just you hate Yisrael even though they did not harm you, I will not wait for you until the last time and the future day of judgment, like I wait for other nations. Rather, I will promptly repay you in this world. In the days of Alexander Mukdan, Tzor, Tzidon and Pelashes were destroyed, and made a permanent desolate mound.

Rashi: It is an expression of zealousness.